It is preferable to buy a new compound microscope rather than a used one when shopping for one. Used ones are frequently abused by students and no longer function properly. Metal construction, achromatic glass lenses, and an easily accessible light bulb are all important features to look for. There are binocular and monocular options, and the choice should be made based on comfort and usage frequency. A binocular compound microscope will cost more than a monocular scope, so choose the compound microscope that best suits your needs and budget.
When it comes to choosing the best compound microscope, the lenses, eyepieces, and basic construction of a microscope are the most important factors to consider. The construction of the microscope is the most basic feature. The frame should be sturdy and made of metal with a reagent-resistant finish. Metal knobs and focus gears with ball bearings around all moving parts are recommended. Avoid toy microscopes that are made of plastic, have plastic lenses, and produce blurry images.
Standard objective lenses should be achromatic, glass lenses that follow the Deutsche Industrie Norm (DIN) standard for threading and length. If the lens isn’t achromatic, it won’t be color-corrected, and you won’t be able to see everything through your scope’s lens. Certain achromatic lenses, such as plan or semi-plan lenses, are more expensive than the standard achromatic lens, which is ideal for students and hobbyists.
Most compound microscopes have three to five objectives with magnification powers ranging from four times to 2,000 times. A 400x magnification is appropriate for biology work, while a 1,000x magnification is preferable for microbiology samples. The magnification power of the objective lenses increases with increasing resolution. Increasing the eyepiece magnification does not improve resolution.
Changeable objectives and eyepieces will be available on some microscopes. For a professional user, changing the eyepiece and objective lenses may be an option. A standard wide-field eyepiece with an 18-millimeter (mm) lens is recommended in all other cases.
In the case of a compound light microscope, the best advice has always been to choose one that uses a fairly common and easily replaceable bulb in case you need one. Tungsten, or incandescent, bulbs are the most cost-effective, but they aren’t always the best option. Fluorescent bulbs are preferable to tungsten bulbs because they produce a whiter light and more accurate colors; they are likely the best choice for student and hobby use. Professional-grade scopes typically use halogen and light-emitting-diode (LED) bulbs, which are more expensive. The halogen and LED options will have a dimmer switch if you want to dim the light.
When using a microscope, the ability to focus on detailed images under magnification is the ultimate goal. As a result, in addition to the coarse adjustment knob, the best compound microscope will have a fine adjustment knob. Although the fine focus is optional, you may not be able to see small details such as an ant’s eye or cellular structures without it.